Eu não estou na frente do meu Mac agora, mas acredito que você pode acionar uma determinada ação dentro de qualquer aplicativo usando as seguintes etapas, no site de suporte da Apple:
Choose Apple menu > System Preferences, and then click Keyboard.
Click Keyboard Shortcuts, and then click the Add (+) button.
Choose an application from the Application pop-up menu. If you want to set the same key combination for a menu command that appears in many applications, choose All Applications.
If the application you want to select does not appear in the list, choose Other and locate the application using the Open dialog. Some applications may not allow you to set keyboard shortcuts.
Type the menu command for which you want to set a keyboard shortcut in the Menu Title field.
You must type the command exactly as it appears in the application menu, including ellipses and any other punctuation. An ellipsis is a special character that looks like three periods. To type an ellipsis, press Option-semicolon, or use the Character Viewer. It may be difficult to know whether the command is written in the menu with a real ellipsis or with three periods, so if one does not work, try the other.